Fifth-wheel coupling
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The fifth-wheel coupling provides the link between a semi-trailer and the towing truck, tractor unit, leading trailer or dolly. The coupling consists of a kingpin, a 2-or-3+1⁄2-inch-diameter vertical
The fifth wheel on a tractor unit, rear view
A fifth wheel, already coupled, side view
A 1920 advertisement for Martin Rocking Fifth Wheel
Road train
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A road train, also known as a land train or long combination vehicle, is a semi-trailer truck used to move road freight more efficiently than single-trailer semi-trailers. It consists of two semi-trai
Fifth-wheel coupling
…in the event of a trailer separation while going down the road. Trailer-to-trailer connection can also be made by using fifth wheels; this creates a B-train. Drawbar (haulage…
A three-trailer livestock road train in Australia
An early road train at Alice Springs on the way to Tennant Creek, c. 1938–1948
A diesel road train in Alice Springs, c. 1938–1939
Livestock road train with Leyland truck in 1962